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Age related macular degeneration in Latinos: risk factors and impact on quality of life

AGE RELATED MACULAR DEGENERATION IN LATINOS:
RISK FACTORS AND IMPACT ON QUALITY OF LIFE
by
Farzana Choudhury
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(EPIDEMIOLOGY)
December 2012
Copyright 2012 Farzana Choudhury

Age related macular degeneration (AMD) is a progressive, potentially irreversible disorder of the macular region of retina that can cause severe loss of central vision in the late stages. Despite the recent advances in the treatment of AMD, it remains the leading cause of blindness in people over the age of 60 in the Western world with significant impact on their health related quality of life (HRQoL). The global prevalence of AMD remains largely unknown and the full impact of this debilitating disease has not been fully characterized. ❧ The relationship between factors influencing incidence and progression of AMD in Latinos and the impact of AMD on HRQoL in Latinos remain largely unexplored. Therefore, to address these issues, I have used the baseline and 4 years cumulative incidence data from the Los Angeles Latino Eye Study (LALES), a population based cohort study of eye disease in Latinos to investigate predictors of AMD incidence and progression and the impact of AMD on HRQoL. In the first chapter I gave an overview of AMD and my primary aims. I discussed briefly about the retina, macula, the definition, brief pathogenesis, grading scheme and classification of AMD. Then, I discussed briefly about what is known about the risk factors of AMD and its impact on HRQoL. Finally I describe the study population and enumerate the primary aims. ❧ In my first paper (chapter 2) I evaluated the risk factors associated with 4 year incidence and progression of AMD. The risk factors were selected based on literature review and expert clinical opinion. Stepwise logistic regression was used to develop parsimonious multivariable predictive models for each AMD end- points. The results from these analyses revealed that older age and higher pulse pressure were independently associated with the incidence of any AMD and different early AMD lesions in this group of Latinos. Additionally, presence of diabetes mellitus was independently associated with increased retinal pigment and male gender was associated with retinal pigment epithelial depigmentation. Older age and current smoking were independently associated with progression of AMD. Some of the findings were similar to those reported by studies in non-Hispanic whites. The interesting and unique finding in this paper was the association of pulse pressure with incidence of some early maculopathies that were not previously reported in Caucasians. Given the equivocal results for risk factors of AMD in other population based studies and the paucity of data in Latinos, these finding will aide in our understanding of AMD in this unique ethnic group. ❧ The short term and long term impact of AMD on quality of life in Latinos has not been investigated to a great extent. Given the unique socio-demographic, ethnic and cultural characteristics of Latinos it is important to estimate the impact of the patient reported outcomes in this unique group of people. Therefore, for my second paper I investigated the association of prevalent AMD and HRQoL, described in the third chapter. Two validated instruments of HRQoL were used to assess general HRQoL and vision specific HRQoL. In this analysis, I assessed and compared covariate-adjusted mean QOL scores between participants without any AMD and participants with different end-point of early and late Maculopathies by using analysis of covariance (ANCOVA). I also calculated Effect sizes (ES) to quantify the impact of HRQoL. AMD is associated with a measurably lower in HRQOL, even for lesions defined as early AMD. There was also evidence of a measurable loss in health related quality of life is associated with lesions defined as early AMD. ❧ Results from my second paper on cross-sectional data lead to conceptualize and design the third paper (chapter 4). In this paper I further evaluate the impact of AMD on HRQoL by investigating the association of intra-individual changes in AMD status with changes in HRQoL status over a 4-year period. For this analysis I looked at the mean changes in QoL scores after adjusting for possible confounders. I applied two methods of analysis to focus on minimally important clinical change and significant individual change. I followed an anchor based approach to define and test a threshold of clinically meaningful change. To further evaluate the impact of AMD on QoL at the individual level, we calculated reliable change index. Results from these analyses confirm a number of the results from the cross-sectional analysis. Overall the results suggest that people with clinically meaningful progression of AMD have diminished health-related quality of life. Even progression to early AMD can have measurable impact independent of other ocular condition. There were also evidence of significant changes with progression of early AMD lesions like soft drusen and pigmentary changes. ❧ To further our knowledge of AMD in Latinos there are many lines of investigation could be undertaken to extend present work. In chapter 5, I summarized our main findings and briefly discussed about these potential future research questions. I believe, results from these studies will help us identify factors that can increase the risk of AMD incidence and further progression in Latinos and will help us to understand the adverse impact of AMD on the quality of life of a sufferer. Further studies will help in developing evidence based screening and intervention programs to reduce incidence and retard the progression of AMD to minimize the negative impact on quality of life.

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AGE RELATED MACULAR DEGENERATION IN LATINOS:
RISK FACTORS AND IMPACT ON QUALITY OF LIFE
by
Farzana Choudhury
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(EPIDEMIOLOGY)
December 2012
Copyright 2012 Farzana Choudhury